Handle case correctly when screen times out and locking immediately

In case the the screen timed out and the setting was set to "lock now"
in case the screen times out, we locked before finished going to sleep,
leading to all kinds of state messups in Keyguard, including an empty
lockscreen when authenticating with fingerprint during that period.

Bug: 23952388
Change-Id: If1629be1171c841d51ec0555422e6108002fdb73